Lung cancer has become the leading cause of cancer-related deaths around the world. In addition to genetic risk factors and smoking, the metabolic risk factors remain to be elusive.To evaluate the associations between obesity, nonalcoholic fatty liver disease (NAFLD) and pulmonary adenocarcinoma in patients with lung cancer.Consecutive operation-proven lung cancer patients with assessment of metabolic disorders and liver ultrasound in 2009 and 2013 were retrospectively enrolled. T-test and multivariate logistic regression were applied to evaluate the contribution of individual factors to lung adenocarcinoma, as well as the synergistic effects between these factors.Among 3664 lung cancer patients with ultrasound examination, 2844 cases were enrolled for further analysis. Of them, 1053 (37.0%) were females, 1242 (43.7%) were cigarette smokers, 1658 (58.3%) were diagnosed as lung adenocarcinoma, 744 (26.2%) had obesity, and 614 (21.6%) had NAFLD. Proportion of female gender, nonsmoker, obesity, NAFLD, and serum lipid levels in patients with adenocarcinoma were significantly higher than those in other subtypes of lung cancer, and in 2013 than in 2009 (all P < .01). NAFLD and obesity were shown as independent factors and positively associated with pulmonary adenocarcinoma, along with female gender and nonsmoking, higher serum levels of cholesterol. NAFLD and other contributing factors exhibited no synergistic effects on adenocarcinoma.Obesity and NAFLD might increase the risk for pulmonary adenocarcinoma, especially in nonsmoking females, and underscore the need for further study into carcinogenic mechanisms and preventive interventions.